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i attempted make myself 2-in-1 programmer can program both at89cx051 , at89s52 on same board without having plugging/unplugging of port. the main issue strobe pin aka reset (rst in circuit). (pin 1 of db25 connector). tested pc , got no results. what seems work if connected rst vcc via 1k resistor. works because though output @ 3.8v instead of 5 (which vcc at), puts at89s52 in reset mode expected, i'm not getting 12v @ pin 1 of small at89cx051 socket. if don't make manual connection, 1.4v measured @ rst, after added 10k resistor between vcc , rst. without rst being forced ground, should 5v i'm not. i have tested transistors manually leg leg using diode setting on multimeter , turned out fine. resistors going base of transistors 2.2k , used 1k resistors in place of diodes. other resistors 10k. resistor going buffer (74hc125) 0 ohm. all capacitors 0.1uf. why getting such awkward voltages reset pin? using weak of resistors or something? update so ended ma...

i know in magnitude spectrum of single square dc pulse (0-8v) lobes 0 @ frequencies $$\frac{1}{t},\frac{2}{t},\frac{3}{t},...etc. $$ t=pulse duration. if square pulse goes -2v 6v, formula 0 points of spectrum still same, ie. $$\frac{n}{t}$$ n=1,2,3... etc. , t=pulse duration? what difference? applying offset signal change spectrum @ dc (frequency of 0hz). if single square pulse goes 0v 8v, value of dc \$\mathcal{f}\{ f(t)\}|_{\omega=0}=0\$. if square wave goes -2v 6v, \$\mathcal{f}\{f(t)\}|_{\omega=0}=-2\cdot\delta(0)\$.

hello have transformer ebay north court 50 amplifier. there not information online. has 400 0 400 volt ht think ran pair of kt66 valves gz34 rectifier dimensions l x b x h 4" 3" 4" if can me out on 1 great the main determiner of transformer power rating material , cross-sectional area of core. sets power level @ core saturate, , manufacturers don't want use more steel absolutely have to. as rough estimate, since these transformers use same kind of steel laminations , same relative geometry, sufficient make judgement based on volume/mass of core. since core majority of total mass of transformer (the windings tiny fraction), weighing enough, why marko made comment.

i using tps61021 boost converter ic increase input voltage 1.2v 3.3v. have designed boost converter application called ti webench. input voltage: 1.2v output voltage: 3.3v min current: 300ma the pcb have designed, measuring 3.3v, efficiency pathetic. below 25%. in bom, ti webench software recommends using 10uf 10v capacitor, using 10uf 6.3v. not able understand why efficiency low? datasheet inductor . below in tabular format have written current values have measured multimeter. fig.1 measurement of current @ different load resistance. fig.2 ti webench application output fig.3 schematic design of boost converter pin = 1.2v × 570ma = 684 mw pout = 3.3v × 105 ma = 346.5 mw efficiency = pout/pin = 346.5/684 = 50.7% how on earth did come 18.42%? similarly, 64% , 70% other 2 loads. these numbers sound pretty me @ these voltages. did webench give efficiency estimates specific configuration?

can sample , recover signals non infinite "length" using nyquist shannon theorem? example if have signal $$ x(t)= u(t+5)-u(t-5) $$ , know sampling period t less 10s (t<10). can recover using nyquist theorem? if not , recover it? edit: have taken fourier transform of signal , : $$x(ω)=2i(\frac{1}{iω}+πδ(ω))sin(5ω)$$ can lead finding period $$\frac{2π}{5} $$ , see if f>= 5/π can recovered. may not possible because used theorem although on finite signal no need think "finite length". though continuous time signals defined infinite time interval, in practice analyse in finite interval only. x(t) defined in interval [-5 5]. the frequency domain representation of such signal infinite bandwidth sinc function. hence not possible define particular sample rate per nyquist theorem, reconstruct without losing information. can sample definite sample rate, implicitly band limits signal. sampled signal after reconstruction through dac , lpf, not pe...

i'm trying make push-pull audio amplifier pair of power darlingtons (tip142 , tip147), i'm having problems biasing. here's diagram of 1 of configurations: here i'm using 3 diodes, used different things in place try correct biasing voltage. with biasing voltage lower 2.2 v (between bases of transistors) has crossover distortion, because there'll small parts of signal none conducting. with 2.2 v or more, both conducting , there's no more distortion, there's problem: current flowing between them escalates heat until take on fire (being starting current isn't great , they're on large heatsink, heatsink doesn't have time heat, fast happens). they're stable biasing voltages lower 2.1 v, there's distortion. the components heating here output transistors, i've cheked , none of resistors or diodes heating up. i've checked if negative feedback help, didn't, because voltage in output doesn't change current flowing t...

according miller effect, within amplifying devices such transistors have inverting voltage gain higher one, there should increased input capacitance increased voltage gain of amplifier. i has been said effect limiting amplifier @ higher frequencies. comes incorporation of method of increasing transistor's bandwidth. 1 of them dominant pole compensation. according wikipedia: "when capacitor introduced between input , output sides of amplifier intention of moving pole lowest in frequency (usually input pole) lower frequencies, pole splitting causes pole next in frequency (usually output pole) move higher frequency." i part when states 2nd pole should moved higher in frequency (that 2nd roll-off), why heck want decrease 1st pole , consequently first gain roll-off begins @ lower frequencies before. what point of it? i mean, shouldn't desired gain vs. frequency curve flat possible, long possible - higher frequencies? addition of capacitor betwee...